Natural Selection and Genetics in Evolution

1. Natural Selection and Genetics in Evolution Biology 1 Fall 2009

2. Standards • B.1.31 - Describe how natural selection provides the following mechanism for evolution: Some variation in heritable characteristics exists within every species, and some of these characteristics give individuals an advantage over others in surviving and reproducing. Understand that the advantaged offspring, in turn, are more likely than others to survive and reproduce. Also understand that the proportion of individuals in the population that have advantageous characteristics will increase. • B.2.4 - Explain that after the publication of Origin of Species, biological evolution was supported by the rediscovery of the genetics experiments of an Austrian monk, Gregor Mendel, by the identification of genes and how they are sorted in reproduction, and by the discovery that the genetic code found in DNA is the same for almost all organisms. • Scientific Thinking – Mathematical and Logical skills http://dc.doe.in.gov/Standards/AcademicStandards/PrintLibrary/docs-science/2006-science-biologyi.doc

3. Objectives • Students will be able to explain who Charles Darwin is. • Students will be able to explain what Darwin proposed about Natural Selection. • Students will be able to explain who Gregor Mendel is. • Students will be able to explain how genetics can affect evolution. • Students will demonstrate knowledge of evolution by natural selection through project presentations.

4. What is evolution? • Cumulative genetic changes occurring in a population over time • Darwin proposed that evolution occurred through natural selection • Natural selection utilizes genetic variation http://www.pbs.org/wgbh/evolution/library/faq/cat01.html#Q01

5. Survival of the Sneakiest • Comic by the Understanding Evolution team • "Survival of the fittest" means that the strong succeed, and the weak fail, right? Well, often that's how it's portrayed, but the real story is a bit trickier. Let's take a closer look at what the crickets do... • Click here for the Comic (also on the wiki): http://evolution.berkeley.edu/evolibrary/article/0_0_0/sneakermales_01

6. Darwin & Natural Selection “Man selects only for his own good; Nature only for that of the being which she tends.” – Charles Darwin • Darwin postulated… • that organisms pass on traits to the next generation • there was competition between members of same species for resources • some organisms were more likely to survive long enough to reproduce based on certain traits • over time, new species would develop due to selection for certain traits Zimmer, C. (2006). Evolution: The Triumph of an Idea. New York: Harper Perennial.

7. Candy Dish Selection - Activity • Natural Selection demonstration • Need a variety of candies (popular and not) and 30 minutes for activity. • Pass a candy dish (with a great variety of treats) around the class several times. • When more than half of the candy is gone, discuss variation among individuals of animal species. Have the students list characteristics that vary in humans by looking around the room. Ask the students why variation is important (i.e. differential survival of individuals). • Hold up the candy bowl and remaining candies so the students can see. Count the remaining candies and write them on the board. Ask students if they remember what candies were originally in the bowl. Write the original set of candy on the board. • Ask the students to list the traits of the candy they selected (i.e. chocolate, large size). These are traits that caused certain candies to be removed. • Make another list of the traits of the candies not selected by the students (bad flavor, small size). These traits allowed the candies to survive. • “So, the fact that there were different candies with different traits resulted in some candies being eaten and others surviving. This is what natural selection does with individuals in a population. Each individual has unique traits; some traits will help an individual survive and some traits do not.” Tang, Carol. (2003). Candy Dish Selection. UCMP Lessons. http://www.ucmp.berkeley.edu/education/lessons/candy_dish.html

8. How Does Natural Selection Work? • One mechanism of evolution • How it works: • Variation in Traits • Green vs. Brown Beetles • Differential Reproduction • Not all individuals survive to reproduce • Birds eat green more than brown • Heredity • Brown beetles have brown offspring • Results in more beneficial trait becoming more common in the population (brown beetles) http://evolution.berkeley.edu/evosite/evo101/IIIENaturalSelection.shtml

9. Finch Beak Size & Feeding Activity • Students draw a card that determines their starting beak size and what type of bean they can eat, as well as how many beans they need to survive. • The students pick a "modification card" from a bag. • A few of the cards include traits that are not suitable for the current "environment" as well as adaptations that are suitable, while the majority of the cards are neutral and produce no change. • The students must follow the card and keep their card a secret. • Students “feed” by scavenging for beans across the room, only able to pick up one at a time (unless their card says differently). The class "feeds" until there isn't any more food. • Everyone counts up how many beans they have. If the students did not collect enough beans their card said they needed to survive, they become offspring for the surviving “birds” and also inherit those birds’ traits. • Before another round of "eating", students pick out another modification card. • The cycle would continue until the students understand that modifications are random or until the end of the scheduled time. • The students should also come to the conclusion that mutations can be helpful, not helpful, or neutral through showing that not only good mutations happen to promote natural selection.

10. Flashy Fish Activity • Professor John Endler traveled to Trinidad in the 1970s to study wild guppies. The guppies live in small streams that flow down the mountains from pool to pool. In this activity, you will take part in an online simulation of Endler's work. You will collect data, formulate a hypothesis, and run a series of experiments. You will find out about the interplay between natural selection and sexual selection in this wild population of guppies. • Print the Flashy Fish: Data form (pdf) and the Flashy Fish: Discussion Questions (pdf), or get them from your teacher. • Launch the Sex and the Single Guppy Web activity. • Select "I'm ready to find out." • Read the text, and click on the pools to investigate the guppy stream more closely. • Then click on "What causes guppy color variation?" Select one of the hypotheses or create your own, and record it on the data form. • Visit the Guppy Gallery. Read about the different types of guppies, their predators, and their habitats. • Click on "simulation." Proceed with the simulation by creating and carrying out a field experiment to gather data to test your hypothesis. Record your data on the form. (You may need to alter your hypothesis if the data does not support it.) • Answer the questions on the Data form. Think about the Discussion Questions and be prepared to discuss your hypothesis, your experiment, and your explanations with the class. • http://www.pbs.org/wgbh/evolution/educators/lessons/lesson4/act2.html

11. Watch the video about Geneticist Pardis Sabeti The class will discuss the following: What did Pardis Sabeti figure out? Why do you think it was considered a scientific breakthrough? Why do you think she describes her breakthrough as a "wonderful scavenger hunt"? What is meant by the term "resistant" in the context of disease-causing organisms? What does being able to drink milk have to do with natural selection? Genetics & Natural Selection http://www.teachersdomain.org/resource/nsn08.sci.life.evo.pardis/ Video: http://www.teachersdomain.org/asset/nsn08_vid_pardis/

12. Gregor Mendel’s Experiment • Mendel used true breeding lines and crossed with opposite traits (purple vs. white) • 1st generation of offspring were all purple (dominant trait) • 2nd generation had 25% white (recessive trait) http://www.rogers.k12.ar.us/users/ehutches/mendel.phtml

13. Breeding Bunnies • In this activity, you will examine natural selection in a small population of wild rabbits. Evolution, on a genetic level, is a change in the frequency of alleles in a population over a period of time. Breeders of rabbits have long been familiar with a variety of genetic traits that affect the survivability of rabbits in the wild, as well as in breeding populations. One such trait is the trait for furless rabbits (naked bunnies). This trait was first discovered in England by W.E. Castle in 1933. The furless rabbit is rarely found in the wild because the cold English winters are a definite selective force against it. • Note: In this lab, the dominant allele for normal fur is represented by F and the recessive allele for no fur is represented by f. Bunnies that inherit two F alleles or one F and one f allele have fur, while bunnies that inherit two fs have no fur. • Procedure found on the Wiki page under Breeding Bunnies. • http://www.pbs.org/wgbh/evolution/educators/lessons/lesson4/act1.html

14. What can Natural Selection and Genetics tell us about Evolution? • Gregor Mendel discovered the mechanism for heredity • Gametes contain one factor (allele) for different traits but not both factors needed to express the traits. • Characteristics are inherited independently from other characteristics (i.e. Eye color and height). • Each inherited trait is determined by two alleles, one from each parent which determine whether a gene will be dominant or recessive. • Evolution & genetics account for variability in a species • Crossing over of chromosomes • Dominant and recessive traits • Independent assortment http://www.mnsu.edu/emuseum/biology/evolution/genetics/mendelsvariation.html

15. Class Presentations • Make a short PowerPoint presentation on one example of evolution by natural selection. • Explain how this evolution occurred. • Use your notes on natural selection to assist in your explanation. • How could Mendel’s ideas on genetics have played a part in your example? • Cite your references

16. Possible Project Topics • Peppered moths in England during the Industrial Revolution • Cichlids in Lake Victoria and the ability to build sand castles • Finch Beak sizes in the Galapagos islands • Sickle Cell in Humans • Or another of your choice, with teacher approval

17. References • http://anthro.palomar.edu/evolve/evolve_2.htm • http://anthro.palomar.edu/synthetic/synth_4.htm • http://dc.doe.in.gov/Standards/AcademicStandards/PrintLibrary/docs-science/2006-science-biologyi.doc • http://evolution.berkeley.edu/evolibrary/article/0_0_0/sneakermales_01 • http://evolution.berkeley.edu/evosite/evo101/IIIENaturalSelection.shtml • http://www.actionbioscience.org/evolution/futuyma.html • http://www.literature.org/authors/darwin-charles/the-origin-of-species/chapter-04.html • http://www.mnsu.edu/emuseum/biology/evolution/genetics/mendelsvariation.html • http://www.pbs.org/wgbh/evolution/educators/lessons/lesson4/act1.html • http://www.pbs.org/wgbh/evolution/educators/lessons/lesson4/act2.html • http://www.pbs.org/wgbh/evolution/library/faq/cat01.html#Q01 • http://www.rogers.k12.ar.us/users/ehutches/mendel.phtml • http://www.teachersdomain.org/resource/nsn08.sci.life.evo.pardis/ • Tang, Carol. (2003). Candy Dish Selection. UCMP Lessons. http://www.ucmp.berkeley.edu/education/lessons/candy_dish.html • Zimmer, C. (2006). Evolution: The Triumph of an Idea. New York: Harper Perennial.